Design of a Low-Loss and Nonvolatile Phase-Modulated Metasurface Working at Ka Band

In this letter, a low-loss and nonvolatile phase-modulated metasurface (PMM) based on germanium telluride (GeTe) is proposed operating in the Ka-band. The main functional part of the element is two opposing gradient T-shaped metal patches, which are connected by the GeTe film. GeTe belongs to the non-volatile phase-change material (PCM) and can achieve reversible switching between low- and high-resistance states. By tuning the state of the GeTe film, a wideband reflection phase reconfiguration of the structure has been realized. The key advantage of this design lies in significantly reducing the metasurface reflection loss via increased aspect ratio of the GeTe film, thereby mitigating the inherent limitation of high insertion loss in PIN-diode-based phase-modulated metasurfaces at high frequency. A prototype fabricated for rectangular waveguide testing was experimentally characterized, with measured results validating the structural design correctness.